A conventional stamping device 50 is disclosed in FIGS. 5A, 5B and 5C, and generally includes a casing 51 and a frame 54 which has one end inserted in the opening of the casing 51 with a spring 55 connected between the inner top of the casing 51 and the outer top of the frame 54. Two slots 541 are defined through two opposite walls of the frame 54 and a printing member 53 is movably received in the frame 54. A pin 52 extends through the printing member 53 and two ends of the pin 52 are movably engaged with the two slots 541. An upper protrusion 542 and a lower protrusion 544 are defined in a side of the each of the slots 541. A turning recess 543 is located between the upper and lower protrusions 542, 544. The printing member 53 has two convex 531 on two sides thereof and the printing member 53 starts to turn when the convex 531 contacts the upper protrusion as shown in FIG. 5B. As shown in FIG. 5C, the convex 531 then rotates 180 degrees in the turning recess 543 and the printing face 532 on the printing member 53 faces downward to stamp on document which is not shown. When releasing the downward force on the casing 51, the frame 54 is pushed away from the casing 51 and the printing member 53 inversely rotates and the pin 52 moves upward relative to the slots 541. Nevertheless, it is difficult to assemble the stamping device and the convex 531; the upper protrusion 542 and the lower protrusion 544 are easily worn out which results in mis-function or mis-movement of the printing member 53.
The present invention intends to provide a stamping device wherein the printing member is rotated by the engagement of the racks on the frame and the teeth on the printing member.